This paper reports on a corpus-based investigation of conventionalized English similes which follow the pattern (as) ADJECTIVE as NOUN GROUP. It begins by describing their formal and semantic characteristics, and then discusses issues of variation, approaches to handling variation, and procedures for establishing the simile lexicon. It reports on the frequencies observed in the Bank of English for as-similes, including their distribution in British English, and compares these to frequencies observed in other corpora. Finally, it speculates on how conventionalized as-similes survive in the lexicon, in spite of their apparent infrequency in (corpus) text; sets out a characterization of as-similes; and suggests some implications for phraseological studies in general.